Removable Trap Stations for Hydrocarbon Flowlines

ABSTRACT

Removable trap stations for hydrocarbon flowlines can be implemented as an apparatus. The apparatus includes a multi-phase fluid receiver body and a tank defining an interior volume. The fluid receiver body is configured to couple to a flowline carrying a multi-phase fluid including solids and liquids. The fluid receiver body includes an inlet portion configured to receive a portion of the multi-phase fluid including a portion of the solids flowing through the flowline into the receiver body. The fluid receiver body includes an outlet portion fluidically coupled to the inlet portion. The portion of the multi-phase fluid is configured to flow from the inlet portion to the outlet portion. The tank is fluidically and detachably coupled to the outlet and is configured to receive and retain the portion of the multi-phase fluid received through the inlet portion

TECHNICAL FIELD

This disclosure relates to flow of multi-phase fluid including solidsand liquids, for example, through flowlines and, more particularly, toremoving the solids from the multi-phase fluid.

BACKGROUND

Hydrocarbons entrapped in sub-surface reservoirs are produced (that is,extracted and raised to the surface) through wellbores formed in thereservoirs. The produced hydrocarbons are transported from the surfaceto other locations (for example, gas-oil separation plants) throughflowlines. The produced hydrocarbons are multi-phase fluids that caninclude at least two of solids, liquids or gases. Solids flowing througha flowline can accumulate over time. Scraping is the practice ofremoving accumulated practices from the flowline.

SUMMARY

This disclosure describes technologies related to removable trapstations for hydrocarbon flowlines.

Certain aspects of the subject matter described in this disclosure canbe implemented as an apparatus. The apparatus includes a multipl-phasefluid receiver body and a tank defining an interior volume. The fluidreceiver body is configured to couple to a flowline carrying amulti-phase fluid including solids and liquids. The fluid receiver bodyincludes an inlet portion configured to receive a portion of themulti-phase fluid including a portion of the solids flowing through theflowline into the receiver body. The fluid receiver body includes anoutlet portion fluidically coupled to the inlet portion. The portion ofthe multi-phase fluid is configured to flow from the inlet portion tothe outlet portion. The tank is fluidically and detachably coupled tothe outlet and is configured to receive and retain the portion of themulti-phase fluid received through the inlet portion.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. The apparatusincludes a valve assembly configured to permit or prevent fluid flowfrom the outlet portion into the tank.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. The valve assemblyincludes a bore valve.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. The valve assembly iscoupled to the outlet portion. The valve assembly remains with theoutlet portion when the valve assembly is closed and the tank isdetached from the fluid receiver body.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. The apparatusincludes a seal configured to fluidically seal the tank to the outletportion.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. The seal is a flangeseal.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. The seal is coupledto the outlet portion.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. The apparatusincludes a sensor assembly coupled to the tank. The sensor assembly isconfigured to determine that the tank is substantially filled withsolids.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. The tank includes atank inlet fluidically coupled to the outlet portion. The sensorassembly is coupled to the tank inlet.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. The sensor assemblyincludes a wave source configured to transmit an electromagnetic wave, awave sensor configured to receive the electromagnetic wave transmittedby the wave source and transmit a signal representing a magnitude of theelectromagnetic wave, and a processor coupled to the wave sensor. Theprocessor is configured to receive the signal from the wave sensor andto determine that the tank is substantially filled with solids based onthe magnitude of the electromagnetic wave.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. The apparatusincludes a weigh scale coupled to the tank. The weigh scale isconfigured to sense a weight of the solids in the tank. The processor isconfigured to determine that the tank is substantially filled withsolids based on the weight sensed by the weigh scale.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. The wave source andthe wave sensor are arranged substantially parallel to the flowline towhich the fluid receiver body is coupled.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. The fluid receiverbody includes a perforated plate member configured to be coupled to theflowline. The perforated plate member can receive the portion of themulti-phase fluid.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. The perforated platemember includes tapered portions that incline away from the flowline andtoward the inlet portion.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. The apparatusincludes an elongated tubular member fluidically coupled to the flowlinedownstream of the fluid receiver body. The elongated tubular member isinclined vertically upward relative to and away from the fluid receiverbody.

Certain aspects of the subject matter described in this disclosure canbe implemented as an apparatus. From a flowline carrying a multi-phasefluid including solids and liquids, a portion of the multi-phase fluidincluding a portion of the solids is received into a multi-phase fluidreceiver body fluidically coupled to the flowline. The portion of themulti-phase fluid is flowed into a tank fluidically and detachablycoupled to the fluid receiver body. After flowing the portion of themulti-phase fluid into the tank, it is determined that the tank issubstantially filled with the solids. In response to determining thatthe tank is substantially filled with the solids, the tank is detachedfrom the fluid receiver body. The fluid receiver body remains coupled tothe flowline after the tank is detached.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. To determine that thetank is substantially filled with the solids, a magnitude of anelectromagnetic wave transmitted by a wave source coupled to the tankand sensed by a wave sensor coupled to the tank is determined.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. A weigh scale coupledto the tank determines a weight of the solids in the tank to determinethat the tank is substantially filled with the solids.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. A valve assemblycoupled to an outlet portion of the fluid receiver body prevents flow ofthe portion of the multi-phase fluid out of the fluid receiver bodybefore detaching the tank from the fluid receiver body.

Aspects of the disclosure combinable with any of the other aspects ofthe disclosure can include the following features. The solids in thetank are emptied and the tank is re-coupled to the fluids receiver body.

The details of one or more implementations of the subject matterdescribed in this specification are set forth in the accompanyingdrawings and the description below. Other features, aspects, andadvantages of the subject matter will become apparent from thedescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an example of a flowline to whichmultiple trap stations are coupled.

FIG. 2A is a schematic diagram of an example of a trap station coupledto the flowline.

FIG. 2B is a schematic diagram of an example of a trap station detachedfrom the flowline.

FIG. 2C is a schematic diagram of a component of the trap station ofFIGS. 2A and 2B.

FIG. 3 is a schematic diagram of the trap station of FIGS. 2A and 2B.

FIG. 4 is a schematic diagram of the trap station of FIGS. 2A and 2B.

FIG. 5 is a flowchart of an example of a process for trapping solidsusing the trap station of FIGS. 2A and 2B.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

This disclosure describes a trap station that can be detachably coupledto a flowline carrying multi-phase fluids (for example, hydrocarbonsproduced from sub-surface reservoirs). The multi-phase fluid includes atleast two of solids, liquids or gases. The trap station is coupled tothe flowline such that some of the multi-phase fluid including solidsflows into the trap station and accumulates over time. When apre-determined quantity of the solids has accumulated, the trap stationcan be detached from the flowline without interrupting the flow of therest of the multi-phase fluids through the flowline. A new trap stationcan be coupled to the flowline in place of the detached trap station.Alternatively, the trap station can be emptied and re-coupled to theflowline. In this manner, solids can be removed from the flowlinewithout interrupting flow through the flowline. Also, the frequency ofuse of scrapers to remove solids from the flowline can also be reduced.Another advantage is to decrease the potential of scrapers getting stuckor slowed down in the pipelines. The trap station can be easilymonitored remotely, reducing the need for personnel interference withthe process.

FIG. 1 is a schematic diagram of an example of a flowline 100 to whichmultiple trap stations (for example, a trap station 102 a, a trapstation 102 b, a trap station 102 c) are coupled. Multi-phase fluidincluding at least two of solids, liquids, or gases can be flowedthrough the flowline 100. For example, one end of the flowline 100 canbe fluidically coupled to a wellhead at the surface of a wellborethrough which hydrocarbons are produced. Another end of the flowline 100can be coupled to a hydrocarbon processing plant (for example, a gas-oilseparation plant). The flowline 100 can be cylindrical with a circular(or other) cross-section. Each trap station can be coupled to the bottomsurface of the flowline 100. That is, each trap station can bepositioned between the flowline 100 and the surface (for example, theground) that supports the flowline 100. In the context of thisdisclosure, “fluidically coupled” means that two structures can becoupled to permit fluid flow between the structures without any leakageof the fluid at the coupling interface. In some instances, the couplingcan be permanent such that the two structures cannot be re-attached upondetachment. In some instances, the coupling can be detachable such thatthe two structures can be re-attached and the fluidic couplingre-established upon detachment.

In this position, a portion of the multi-phase fluid that includessolids and liquids can flow from the flowline 100 into a trap stationdue to gravity while a remainder of the multi-phase fluid continues toflow through the flowline 100. The solids settle to the bottom of thetrap station and, over time, accumulate in the trap station. Once thetrap station has been filled with a pre-determined amount of solids,then the flow of the multi-phase fluid into a portion of the trapstation can be ceased, and the trap station can be detached from theflowline 100, as explained in detail below.

In the context of this disclosure, the multi-phase fluid flowed throughthe flowline 100 includes hydrocarbons that include solids such as sand.The trap station described here can be used with other flowlines throughwhich other multi-phase fluids carrying solids are flowed. Also, theflowline 100 can extend over long distances, for examples, hundreds orthousands of kilometers. Multiple trap stations can be coupled to theflowline 100 at respective locations to increase a quantity of solidstrapped in the trap stations.

FIG. 2A is a schematic diagram of the trap station 102 a coupled to theflowline 100. Other trap stations that can be coupled to the flowlinecan be substantially identical to the trap station 102 a. The trapstation 102 a includes a multi-phase fluid receiver body 202 that can befluidically coupled to the flowline 100, for example, to the bottomportion of the flowline 100. The fluid receiver body 202 can include aninlet portion 206 that can receive a portion of the multi-phase fluid204 that includes a portion of the solids flowing through the flowline100 into the fluid receiver body 202. The fluid receiver body 202 caninclude an outlet portion 208 coupled to the inlet portion 206. Forexample, the inlet portion 206 and the outlet portion 208 can be coupledby an elongated tubular member through which the portion of themulti-phase fluid 204 can flow. The elongated tubular member can have acircular or other cross-sectional shape. The trap station 102 a caninclude a tank 210 defining an interior volume 212. The tank 210 can befluidically and detachably coupled to the outlet 208 and can receive andretain the portion of the multi-phase fluid 204 received through theinlet portion 206.

The tank 210 is detachably, fluidically coupled to the flowline 100.FIG. 2B is a schematic diagram of the trap station 102 a detached fromthe flowline 100. When the tank 210 is fluidically coupled to theflowline 100, the portion of the multi-phase fluid 204 can flow from thefluid receiver body 202 into the tank 210. The tank 210 is detachable inthat, at any time, the flow of the portion of the multi-phase fluid 204can be ceased, and the tank 210 can be detached from the fluid receiverbody 202, as shown in FIG. 2B. When the tank 210 is detached, fluid doesnot flow out of the fluid receiver body 202. The tank 210 can bere-attached to the fluid receiver body 202, and the fluidic coupling canbe restored such that the portion of the multi-phase fluid 204 from thefluid receiver body 202 into the tank 210 resumes.

Fluid flow from the fluid receiver body 202 into the tank 210 can becontrolled (that is, permitted or prevented) by a valve assembly 216,for example, a bore valve or other type of valve. In someimplementations, the valve assembly 216 is coupled to the outlet portion208 such that the valve assembly 216 remains with the outlet portion208, that is, remains with the fluid receiver body 202, when the tank210 is detached from the fluid receiver body 202. In suchimplementations, the valve assembly 216 can be in a closed state toprevent fluid flow out of the flowline 100 through the fluid receiverbody 202.

In some implementations, the tank 210 can be sealed to the outletportion 208 by a seal 218, for example, a flange seal or other seal. Theseal 218 can be coupled to the outlet portion 208 such that the seal 218remains with the outlet portion 208, that is, remains with the fluidreceiver body 202, when the tank 210 is detached from the fluid receiverbody 202. Alternatively, the seal 218 can be coupled to the tank inlet228 such that the seal 218 is detachable with the tank 210. In someimplementations, the seal 218 can include a component that remains withthe outlet portion 208 and another component that is detachable with thetank 210. The two components can mate to fluidically seal the tank 210to the outlet portion 208 when the tank 210 is fluidically coupled tothe fluid receiver body 202.

FIG. 2C is a schematic diagram of a perforated plate member 228 of thetrap station of FIGS. 2A and 2B. The plate member 228 can be coupled,for example, permanently attached by welding or other permanentattachment techniques, to the flowline 100. Because the plate member 228is permanently, fluidically coupled to the flowline 100 and because thefluid receiver body 202 is permanently, fluidically coupled to the platemember 228, a portion of the trap station 102 a remains fluidicallycoupled to the flowline 100 when the tank 210 is detached, for example,to empty the accumulated solids.

In some implementations, the inlet portion 206 can include or be definedby the plate member 228. The perforations (for example, perforations 230a, 230 b) can be sized to permit solids in the multi-phase fluid flowingthrough the flowline 100 to enter the fluid receiver body 202. That is,the perforations are not sized to prevent the solids from entering thetrap station 102 a; rather, are sized to permit the solids to enter thetrap station 102 a. In some implementations, the plate member 228 caninclude tapered portions (for example, tapered portions 232 a, 232 b)that incline away from the flowline 100 and toward the inlet portion 204to facilitate flow of the portion of the multi-phase fluid 204 into thetrap station 102 a.

As described earlier, the trap station 102 a can determine that the tank210 has accumulated a pre-determined quantity of solids. In someimplementations, to do so, the trap station 210 can include a sensorassembly 220 that includes a wave source 224, a wave sensor 222 and aprocessor 226. The sensor assembly 220 can be coupled to the tank inlet228 and can reside within the interior volume 212 of the tank 210. Insome implementations, the wave source 224 and the wave sensor 222 can bearranged substantially parallel to the flowline 100 to which the fluidreceiver body 202 is coupled. For example, the wave source 224 and thewave sensor 222 can be arranged to be apart with a space in between (forexample, on two opposite sides of the tank inlet 228. The portion of themulti-phase fluid 204 can flow through the space in between the wavesensor 222 and the wave source 224.

The wave source 224 can transmit an electromagnetic wave. The wavesensor 222 can receive the electromagnetic wave transmitted by the wavesource 224 and transmit a signal representing a magnitude of theelectromagnetic wave. The processor 226 is coupled to the wave sensor222. The processor 226 can receive the signal from the wave sensor 222and determine that the tank 210 is substantially filled with solidsbased on the magnitude of the electromagnetic wave. In someimplementations, the wave source 224 can send a constant signal (forexample, constant amplitude, frequency over time) that is received bythe wave sensor 222. An absence of a change in a signal value sensed bythe wave sensor 222 indicates an absence of any interfering solidparticles in the tank 210. When solids accumulate in the tank to a levelat which the wave source 224 and the wave sensor 222 are positioned,then the solids interfere with the signal resulting in a change (forexample, a decrease) in the signal value sensed by the wave sensor 222.In response, the processor 226 can initiate operations directed toreplacing or emptying the tank 210

In the context of this disclosure, “substantially filled” means that thetank 210 includes sufficient solids to warrant closing the valveassembly 216 to detach the tank 210 from the fluid receiver body 202 andremove the solids from the tank 210. In some implementations, the tank210 can be substantially filled with solids when the solids reach thespace between the wave sensor 222 and the wave source 224.

In some implementations, the tank 210 can be substantially filled withsolids when a pre-determined weight in the tank 210 is reached. FIG. 3is a schematic diagram of the trap station 102 a including a weigh scale302. The weigh scale 302 can be positioned inside the tank 210 orattached to the outside and at the bottom of the tank 210. As theportion of the multi-phase fluid 204 flows into the tank 210, the weightregistered by the weigh scale 302 can increase. When the weight reachesa pre-determined weight threshold, the weigh scale 302 can transmit asignal indicating that the tank 210 is substantially filled with solids.

In response to determining that the tank is substantially filled withsolids, a signal can be transmitted to the valve assembly 216 toautomatically switch from an open state to the closed state. Forexample, the processor 226 can be operatively coupled to the valveassembly 216 and can transmit instructions to the valve assembly 216 tobe opened or closed. In another example, the weigh scale 302 can beoperatively coupled to the valve assembly 216 like the processor 226.When the processor 226 or the weigh scale 302 determines that the tank210 is substantially filled with solids, the processor 226 or the weighscale 302 can transmit an instruction to the valve assembly 216 to beclosed. In response, the valve assembly 216 can automatically, that is,without user intervention, close, thereby preventing further flow of themulti-phase fluid from the fluid receiver body 202 into the tank 210.Alternatively, the processor 226 or the weigh scale 302 can transmit asignal indicating that the tank 210 is substantially filled with solidseither over a wired or wireless connection, for example, to a terminalmonitored by operations personnel. The personnel can then manually closethe valve assembly 216. With the valve assembly 216 closed, thepersonnel can detach the tank 210 from the fluid receiver body 202.

FIG. 4 is a schematic diagram of the trap station 102 a of FIGS. 2A and2B. In some implementations, the trap station 102 a can include anelongated tubular member 402 fluidically coupled to the flowline 100downstream of the fluid receiver body 202. The elongated tubular member402 can be oriented, for example, inclined vertically upward relative toand away from the fluid receiver body 202. The orientation of theelongated tubular member 402 can be selected such that a speed of thesolids in the multi-phase fluid flowing through the tubular member 402are slowed, for example, because of gravity as the solids climb theincline. Under gravity, the solids can fall backward into the fluidreceiver body 202 and accumulate in the tank 201.

FIG. 5 is a flowchart of an example of a process 500 for trapping solidsusing the trap station of FIGS. 2A and 2B. Certain process steps of theprocess 500 can be implemented by a solids trap station, for example,one of the trap stations (such as trap station 102 a) described earlier.Certain process steps can be implemented by operations personneloperating or maintaining (or both) a flowline through which multi-phasefluids are flowed. At 502, multi-phase fluid including solids isreceived into a fluid receiver body, for example, the fluid receiverbody 202. At 504, the multi-phase fluid is flowed into a tank detachablycoupled to the fluid receiver body, for example, the tank 210detachably, fluidically coupled to the fluid receiver body 202. At 506,it is determined that the tank is substantially filled with solids. Forexample, either the processor 226 or the weigh scale 302 can determinethat the tank 210 is substantially filled with solids. At 508, the tankis detached from the fluid receiver body to empty the solids. Forexample, the valve assembly 216 can be closed, either responsive to aninstruction from the processor 226 or the weigh scale 302 or byoperations personnel. Subsequently, the tank 210 can be detached fromthe fluid receiver body 202. The solids in the tank 210 can be emptied,the tank 210 can be re-attached to the fluid receiver body 202, and thevalve assembly 216 can be re-opened.

Thus, particular implementations of the subject matter have beendescribed. Other implementations are within the scope of the followingclaims.

1. An apparatus comprising: a multi-phase fluid receiver bodyfluidically configured to couple to a flowline carrying a multi-phasefluid comprising solids and liquids, the fluid receiver body comprising:an inlet portion configured to receive a portion of the multi-phasefluid comprising a portion of the solids flowing through the flowlineinto the fluid receiver body, and an outlet portion fluidically coupledto the inlet portion, the portion of the multi-phase fluid configured toflow from the inlet portion to the outlet portion; and a tank definingan interior volume, the tank fluidically and detachably coupled to theoutlet and configured to receive and retain the portion of themulti-phase fluid received through the inlet portion.
 2. The apparatusof claim 1, further comprising a valve assembly configured to permit orprevent fluid flow from the outlet portion into the tank.
 3. Theapparatus of claim 2, wherein the valve assembly comprises a bore valve.4. The apparatus of claim 2, wherein the valve assembly is coupled tothe outlet portion, wherein the valve assembly remains with the outletportion when the valve assembly is closed and the tank is detached fromthe fluid receiver body.
 5. The apparatus of claim 1, further comprisinga seal configured to fluidically seal the tank to the outlet portion. 6.The apparatus of claim 5, wherein the seal comprises a flange seal. 7.The apparatus of claim 5, wherein the seal is coupled to the outletportion.
 8. The apparatus of claim 1, further comprising a sensorassembly coupled to the tank, the sensor assembly configured todetermine that the tank is substantially filled with solids.
 9. Theapparatus of claim 8, wherein the tank comprises a tank inletfluidically coupled to the outlet portion, wherein the sensor assemblyis coupled to the tank inlet.
 10. The apparatus of claim 8, whereinsensor assembly comprises: a wave source configured to transmit anelectromagnetic wave; a wave sensor configured to receive theelectromagnetic wave transmitted by the wave source and transmit asignal representing a magnitude of the electromagnetic wave; and aprocessor coupled to the wave sensor, the processor configured toreceive the signal from the wave sensor and to determine that the tankis substantially filled with solids based on the magnitude of theelectromagnetic wave.
 11. The apparatus of claim 10, further comprisinga weigh scale coupled to the tank, the weigh scale configured to sense aweight of the solids in the tank, wherein the processor is configured todetermine that the tank is substantially filled with solids based on theweight sensed by the weigh scale.
 12. The apparatus of claim 10, whereinthe wave source and the wave sensor are arranged substantially parallelto the flowline to which the fluid receiver body is coupled.
 13. Theapparatus of claim 1, wherein the fluid receiver body comprises aperforated plate member configured to be coupled to the flowline, theperforated plate member to receive the portion of the multi-phase fluid.14. The apparatus of claim 13, wherein the perforated plate membercomprises tapered portions that incline away from the flowline andtoward the inlet portion.
 15. The apparatus of claim 1, furthercomprising an elongated tubular member fluidically coupled to theflowline downstream of the fluid receiver body, the elongated tubularmember inclined vertically upward relative to and away from the fluidreceiver body.
 16. A method comprising: from a flowline carrying amulti-phase fluid comprising solids and liquids, receiving a portion ofthe multi-phase fluid comprising a portion of the solids into amulti-phase fluid receiver body fluidically coupled to the flowline;flowing the portion of the multi-phase fluid into a tank fluidically anddetachably coupled to the fluid receiver body; after flowing the portionof the multi-phase fluid into the tank, determining that the tank issubstantially filled with the solids; and in response to determiningthat the tank is substantially filled with the solids, detaching thetank from the fluid receiver body, wherein the fluid receiver bodyremains coupled to the flowline after the tank is detached.
 17. Themethod of claim 16, wherein determining that the tank is substantiallyfilled with the solids comprises determining a magnitude of anelectromagnetic wave transmitted by a wave source coupled to the tankand sensed by a wave sensor coupled to the tank.
 18. The method of claim17, wherein determining that the tank is substantially filled with thesolids comprises determining, by a weigh scale coupled to the tank, aweight of the solids in the tank.
 19. The method of claim 16, furthercomprising preventing, by a valve assembly coupled to an outlet portionof the fluid receiver body, flow of the portion of the multi-phase fluidout of the fluid receiver body before detaching the tank from the fluidreceiver body.
 20. The method of claim 18, further comprising: emptyingthe solids in the tank; and re-coupling the tank to the fluids receiverbody.